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Resources for Understanding Low Falling Numbers

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2016 Washington Wheat Industry Resources for Understanding the Low Falling Number Issue

The following resources were assembled to help growers and wheat industry members understand issues surrounding low falling number in wheat.

Washington Association of Wheat Growers and the Washington Grain Commission

Washington State University and the USDA-ARS

Idaho Wheat Commission

View this page in PDF format.

Washington Association of Wheat Growers Falling Number Update

Falling Number Blues Low falling numbers, which have struck distinct regions of Eastern Washington periodically have shown up once again in the 2016 crop. This season’s outbreak is widespread, but on a random basis. Low falling numbers can be caused by two factors: rain at harvest and Late Maturity Alpha Amylase (LMA) activity. This year,… » More ...

Recent Weather Could Affect Wheat Quality

As wheat harvest gets started in Washington, recent rainfall and cool temperatures have some growers worried about Mother Nature’s fickle ways with their crop.  Rainfall close to harvest can result in preharvest sprouting, which can negatively affect wheat quality.  Dr. Camille Steber, USDA-ARS plant geneticist, explains the potential effects of recent rains on this year’s wheat crop and what growers can do to manage this risk.

Fig. 1. Sponge cakes fall with increasing alpha-amylase from sprouting– image from WWQL, USDA-ARS, Pullman

The Hagberg-Perten Falling Number test is used to measure starch damage due to sprout.  Low FN is used as an indicator that grain contains a high level of alpha-amylase, an enzyme that degrades starch leading to poor end-use quality of wheat products (Figure 1).  Grain with an FN below 300 seconds is typically discounted in the Pacific Northwest.

Wheat that has been rained on is at risk of low FN.  Eastern Washington experienced periods of rainfall July 7 to 12, 2016, just as winter wheat harvest approached.  Chances are, buyers will check FN to protect themselves from sprout damage risk.  Whether or not your grain is likely to have low FN problems depends on the susceptibility of the cultivar you grew, on the local weather, and the timing of the rain relative to maturity date.

Fig. 2. The chances that rain will induce sprouting and low FN increase the longer the wheat “after-ripens” or sits dry on the mother plant after the wheat turns matures (turns yellow). Thus, dormancy and sprouting tolerance are lost as the wheat stands in the field.
Fig. 2. The chances that rain will induce sprouting and low FN increase the longer the wheat “after-ripens” or sits dry on the mother plant after the wheat turns matures (turns yellow). Thus, dormancy and sprouting tolerance are lost as the wheat stands in the field.

Preharvest sprouting is the initiation of grain germination while still on the mother plant.  Germinating seeds degrade starch for use in fueling growth.  Lack of seed dormancy explains 60-80% of genetic sprout susceptibility.  Dormant grains can’t germinate, and so don’t suffer sprout damage in the rain.  Seed dormancy is strongest at maturity, just as the wheat turns from green to yellow.  Dormancy is lost gradually over time as the dry, mature grain “after-ripens” (Figure 2).  Winter wheat that still had some green color is less likely to have a low FN due to sprouting than wheat that was completely yellow and dry when it rained.  Since green grain cannot sprout, spring wheat that was green when it rained should be safe from low FN, as long as there isn’t another ill-timed rain event.

Not all rainstorms induce sprouting.  Seed dormancy is broken by cool, rainy conditions.  So if the temperatures are in the 80s °F when it rains, the wheat is less likely to sprout than if the temperatures are in the 60s.  Low FN is also more likely when there are multiple rainy days in a row, as the wheat stays wet longer.

How do you spot sprouted grain?

Fig. 3. A sprouted grain with a seedling root just poking out of the grain is not obviously germinated, but has low FN/high amylase.
Fig. 3. A sprouted grain with a seedling root just poking out of the grain is not obviously germinated, but has low FN/high amylase.

It takes a lot of rainfall to make a seedling sprout out from a wheat spike (about 3 days of constant rain at 70 degrees).  If you look closely at a mildly sprouted grain, you can sometimes see a small root protruding from the germ-end (Figure 3).  Such grain can have a very low FN (under 200 sec).  As the sprouted grain dries, the root can shrink back into the grain leaving behind a small crack at the embryo end.  Sometimes this cracked end breaks, leaving behind a germ-less grain.  So get out your magnifying glass.

Low FN (200-300 sec) can also be caused by late-maturity alpha-amylase (LMA) induced by heat shock or cold shock during grain maturation.  LMA causes low FN in grain that appears to be sound. We had some big temperature fluctuations this summer, so there may be some lower FN in wheat that saw no rain.  Some LMA-susceptible suspects include SY-Ovation, Bruehl, Jasper, and Alturas.

Plant cultivars with genetic resistance to sprouting and LMA.  We can use past preharvest sprouting events to judge which cultivars have more genetic resistance to sprouting.  For example, there were major sprouting events in Fairfield, Lamont, Pullman, and other locations in 2013.  The FN of all cultivars grown in the WSU Cereal Variety Trial at all locations in 2013 and 2014 can be found on the Project 7599 PNW Falling Number website.  One problem is that many of the highly PHS tolerant cultivars such as Mary and Masami are older cultivars that may not compare well to recent cultivars for yield and disease resistance.  The falling number versus yield tool on the Project 7599 website can help you take both yield and FN into account when choosing a cultivar (http://steberlab.org/project7599data.php#anchor2013Results).  Examples of sprouting-resistant cultivars include Puma, Skiles, Coda, and Bobtail.  Sprouting-susceptible cultivars include Bruehl, Xerpha, AP-Legacy, LWW10-1018, and Bruneau.  Ongoing research will improve sprouting resistant choices.

Harvest wheat quickly after maturity to reduce risk of getting rained on.  Wait for the rained-on wheat to dry well before harvesting to avoid germination in the truck.  Also, avoid harvesting green wheat, as green kernels have higher alpha-amylase (lower FN) than mature grain.  Green kernels can be a problem if you combine wheat that is yellow on the hill with green wheat from the draw.

Avoid mixing likely-sprouted grain with likely-unsprouted grain.  A little bit of alpha-amylase can cause big FN problems.  Mixing equal amounts of FN 200 grain with FN 400 grain will not give you a load at FN 300 sec.  Instead you will end up with something well below 300.  If you have one field that was greenish and another field that was fully yellow when it rained, you might make more money if you keep them separated when you sell.  The same is true if you planted both a sprouting-resistant and susceptible cultivar in separate fields.
Store mildly sprouted grain.  Some research suggests that alpha-amylase levels drop during storage – it could be that UV light or heat degrades the enzyme over time.  If the FN is moderately low (200-300 sec), it might help to store grain for 2 to 3 months to see if the FN rises.  If the FN is very low, storing the grain won’t reverse starch damage that has already occurred.  So storing the grain may not greatly improve its value.

If you want to read more about the Falling Number test and sprout damage, see:
“Preventing those Falling Numbers Blues” – Wheat Life  (http://steberlab.org/pubs/2013c.pdf)
“Falling Numbers: research strategies to stay out of the red.” – Wheat Life (http://steberlab.org/pubs/2014d.pdf)
2013 and 2014 Falling Number Data (http://steberlab.org/project7599data.php#anchor2014Results)


Camille Steber is a molecular geneticist with the USDA-ARS in Pullman, WA. For questions/comments, contact her at csteber@wsu.edu or 509-335-2887.

Organic Case Studies Publication

The latest bulletin published by the Small Grains Team is PNW683 – Organic Small Grain Production in the Pacific Northwest: A Collection of Case Studies. The publication includes 12 case studies of organic grain farms that encompass three precipitation zones of the rainfed Inland Northwest, plus farms using full- and supplemental irrigation.

The farmers interviewed for the case studies discussed their philosophy for organic farming, methods of transition to organic production, crop rotation, soil fertility, seedbed preparation, plus weed and pest management. They also discussed marketing methods and techniques that had worked well (or not) on their farms. In addition, they offered tidbits of advice for farmers considering organic production.

As the case studies are comprised of individual’s experiences and opinions, they do not constitute formal recommendations by WSU Extension. Each case study does include complementary and pertinent information on the National Organic Rules and Certification.

PNW683 is available, free of charge. Go to the Organic Production button on the left side of the page, then click on Case Studies. The online version of the document includes hyperlinks to other sections or websites. These links are lost in the printed version.


If you encounter any problems with these links or when downloading files, please contact Blythe Howell at blythe.howell@wsu.edu as this publication is unique in its size and complexity.

The case studies were authored by Louise Lorent, Associate in Research; Diana Roberts, PhD; and Ian Burke, PhD. Funds were provided by a grant from OREI (Organic Research and Extension Initiative) and a Hatch Project.

For questions regarding the case studies, contact Diana Roberts at robertsd@wsu.edu.

Soil Acidification Video Series

Awareness of soil acidification has been growing in the inland Pacific Northwest (iPNW). Farmers, Researchers, and Industry Professionals have been finding that this emerging regional issue has generated more questions than answers. Soil acidification can affect crops and nutrient availability, as well as pathogens and herbicide use. Growers faced with low pH soil can be challenged by the question of what to do about it.

WSU Extension has released a series of three short videos featuring growers and local researchers explaining the challenges, symptoms, causes, and implications for farm management that are associated with soil pH decline.


“Soil Acidity- What it looks like” this video focuses on the symptomology of crops being affected by low soil pH, and other factors that may confound identification of acidic soil.


“Soil Acidity- How it happens” this video focuses on why the Palouse region is experiencing a decline in soil pH, and how it is often seen distributed through the landscape and soil profile.


“Soil Acidity- managing it on the farm” this video discusses how low pH soil can affect management decisions on the farm, and ways of mitigating the impact of soil acidity on crops.


For questions contact Carol McFarland at carol.mcfarland@wsu.edu.

Continue Monitoring Spring Wheat and Barley for Stripe Rust

The most recent and likely last Stripe Rust Update of the season from Dr. Xianming Chen, USDA-ARS Pullman, came out last Friday, June 17. Although stripe rust development was slowed some by the warm temperatures in late May and early June, recent cool conditions have allowed for continued stripe rust development. Winter wheat crops across… » More ...

Ammonium Sulfate as a Water Conditioner to Improve Glyphosate Efficacy

Water is a universal solvent that serves as the primary carrier for pesticide applications. The quality of the water used as a carrier can have a large influence on the performance of herbicides such as glyphosate. Dissolved cations such as calcium, magnesium, zinc, iron, and manganese form complexes with glyphosate that reduce its efficacy.

Ammonium sulfate (AMS) conditions water by reacting with the dissolved cations to form insoluble sulfates that will not react with glyphosate. Spray grade AMS should be added to the spray tank and thoroughly mixed before adding glyphosate.

Here is a handy calculator that uses data from a standard water quality test to determine the amount of AMS to add to your spray tank, in pounds of AMS per 100 gallons of water. The calculator uses an equation developed at North Dakota State University (Nalewaja and Matysiak, 1993) to determine the required amount of AMS needed to neutralize the effects of cations in the water on glyphosate activity. Adding more AMS than called for to neutralize the effects of cations may improve glyphosate activity by providing extra N that helps weak acid herbicides like glyphosate pass through cell membranes. The addition of 8.5 to 17 pounds of AMS per 100 gallons of water is generally recommended to improve glyphosate activity. Liquid forms of AMS are equally effective if used at equivalent rates.

Give the calculator a try and see what you think.


Questions may be directed to Wayne Thompson wayne.thompson@wsu.edu (509-524-2691) or to Drew Lyon drew.lyon@wsu.edu (509-335-2961).

It’s Seed Buying Time!

Spring is in the air in some areas of the Pacific Northwest with others still under snow. Planting season is almost here, bringing with it the latest seed buying resources.

The Washington State Crop Improvement Association’s (WSCIA) 2016 Certified Seed Buying Guide is available both online and from local seed dealers. Produced with help from the WSU Crop and Soil Sciences Department, it covers variety performance for legumes, wheat, and barley, and planting rate based on seeds per square foot. The guide also has a certified seed source list.

The WSU Oilseed Cropping Systems (WOCS) website has several updated resources:

  • Spring oilseed supply list from Pacific Northwest seed dealers and retail outlets — Canola, mustard, camelina, sunflower, safflower, and flax are all available. The crucifer seed quarantine now applies to eastern Washington counties. All seed must be tested for blackleg, and be certified blackleg-free. Every bag should have a Washington State Department of Agriculture-issued tag. This includes cover crop mixtures containing cruciferous crops such as canola, radish, and others.
  • USDA-ARS/WSU 2015 winter canola variety trial results from Okanogan and Pomeroy
  • University of Idaho 2015 spring canola variety trial report from four locations in Idaho and three locations in Washington
  • A Whole-Farm Revenue Protection presentation that was given at the WSU Oilseed Workshops. March 15 is the whole-farm revenue protection and insurance coverage deadline for spring crops.

For more information about the WSCIA seed buying guide or the cereal variety testing program, contact Ryan Higginbotham (rhigginbotham@wsu.edu or 509-335-1205). Karen Sowers (ksowers@wsu.edu or 509-396-5936.) can answer questions about oilseed suppliers and the WOCS program.

Spring wheat, barley, peas, canola, and winter wheat in a research field. Photo by Stephen Guy.
Spring wheat, barley, peas, canola, and winter wheat in a research field. Photo by Stephen Guy.
Washington State Department of Agriculture Tag
Washington State Department of Agriculture Tag

New Publication Has Washington Agribusiness Focus

Washington Agribusiness Status and Outlook cover photo_Page_01 Washington Agribusiness: Status and Outlook 2016 is the inaugural issue of a new annual publication. Produced by WSU economic sciences faculty, it examines the opportunities and challenges facing Washington agriculture. Each issue will come out in January and will provide an update on Washington’s major sectors, including wheat and barley, specialty crops, tree fruit, beef, and dairy, as well as feature articles on specific issues unique each year.

A major focus this year is on the Trans Pacific Partnership trade agreement currently awaiting action by the U.S. Congress. In his article, “Status of Washington Agricultural International Exports,” writer Andrew Cassey highlights the importance of trade to Washington agriculture and discusses potential impacts of the trade agreement. Writer Randy Fortenbery gives the small grains economic forecast in his piece “Situation and Outlook for Small Grains.” In addition, there are two interesting articles that review the results of recently completed research projects that focus on the beef and hard cider sectors in Washington.

Executive editor Randy Fortenbery, who is also a professor in the School of Economic Sciences, intends Washington Agribusiness: Status and Outlook 2016 to provide a concise summary of the issues facing Washington agribusiness. Timothy Nadreau, managing editor, welcomes suggestions for future content. He can be reached at timothy.nadreau@wsu.edu.

Washington State University